Check in codegen test expectations.

test/codegen/expect/language/mixin_implements2_test.js

+dart_library.library('language/mixin_implements2_test', null, /* Imports */[
+  'dart_sdk'
+], function load__mixin_implements2_test(exports, dart_sdk) {
+  'use strict';
+  const core = dart_sdk.core;
+  const dart = dart_sdk.dart;
+  const dartx = dart_sdk.dartx;
+  const mixin_implements2_test = Object.create(null);
+  let VoidTovoid = () => (VoidTovoid = dart.constFn(dart.definiteFunctionType(dart.void, [])))();
+  mixin_implements2_test.A = class A extends core.Object {};
+  mixin_implements2_test.S = class S extends core.Object {};
+  mixin_implements2_test.M = class M extends core.Object {};
+  mixin_implements2_test.C = class C extends dart.mixin(mixin_implements2_test.S, mixin_implements2_test.M) {
+    new() {
+      super.new();
+    }
+  };
+  mixin_implements2_test.main = function() {
+    new mixin_implements2_test.C();
+  };
+  dart.fn(mixin_implements2_test.main, VoidTovoid());
+  // Exports:
+  exports.mixin_implements2_test = mixin_implements2_test;
+});